1. Field of the Invention
The present invention relates to high-frequency modules that enable communication in a plurality of frequency bands using a common antenna, for example, in multi-band communication.
2. Description of the Related Art
Many recent information communication apparatuses and the like, such as cellular phones, have a function that allows a single apparatus to utilize a plurality of frequency bands (multiple bands). In a communication apparatus having such a function, for example, a plurality of circuit devices such as demultiplexers are mounted on a single high-frequency-circuit multilayer substrate to support a plurality of frequency bands. In this case, when a plurality of circuit devices are mounted on a multilayer substrate, the size of the multilayer substrate is increased. Hence, for example, a module has been proposed in which a common antenna is used for a plurality of frequency bands instead of using a plurality of antennas for respective frequency bands, thereby decreasing the number of circuit devices mounted on a multilayer substrate and suppressing an increase in size (refer to, for example, Japanese Unexamined Patent Application Publication No. 2008-271420).
FIG. 1 is a schematic diagram illustrating a switch module disclosed in Japanese Unexamined Patent Application Publication No. 2008-271420. The switch module disclosed in Japanese Unexamined Patent Application Publication No. 2008-271420 includes an FET switch circuit 100 functioning as a multi-port device (SPnT (single-input multiple-outputs)) switch. The FET switch circuit 100 is a switch for switching a transmission path through which a transmission/reception signal of a communication system passes, and connects a terminal A connected to a common antenna 110 to one of terminals B to F which are connected to filter circuits 101 to 105 corresponding to respective frequency bands or a demultiplexer 106. As a result, communication in a plurality of frequency bands can be realized using a common antenna, in Japanese Unexamined Patent Application Publication No. 2008-271420.
However, there is a problem in that, in Japanese Unexamined Patent Application Publication No. 2008-271420, when a design change is made in such a manner that the number of terminals connected to the outside is changed, the FET switch circuit needs to be changed or provided in a corresponding greater number, thereby making it difficult to make a design change in Japanese Unexamined Patent Application Publication No. 2008-271420.